From Tolkien Gateway
- "And here in Rivendell there live still some of his chief foes: the Elven-wise, lords of the Eldar from beyond the furthest seas. They do not fear the Ringwraiths, for those who have dwelt in the Blessed Realm live at once in both worlds, and against both the Seen and the Unseen they have great power."
- ― Many Meetings
The Seen are material objects and living, breathing creatures. However strong personalities like High Elves had also a different form in the Unseen realm.